# 请在...补充一行或多行代码
import turtle


def koch(size, n):
    if n == 0:
        turtle.fd(size)
    else:
        for angle in [0, 60, -120, 60]:
            turtle.left(angle)
            koch(size / 3, n - 1)


def main(level):
    turtle.setup(600, 600)
    turtle.penup()
    turtle.goto(-200, 100)
    turtle.pendown()
    turtle.pensize(2)
    koch(400, level)
    turtle.right(120)
    koch(400, level)
    turtle.right(120)
    koch(400, level)
    turtle.hideturtle


try:
    level = eval(input("请输入科赫曲线的阶: "))
    main(level)
except:
    print("输入错误")
